SPOILER ALERT
Solutions to,
- Exercise 1. Operating on the first and last items
Produce an adverb a1 such that u a1 produces {. u {: where u is a verb,
for example,
erase'u'
1
u a1
{. u {:
* a1
{. * {:
* a1 2 3 5 7
14
in,
10
9
8
7
6
5
4
3
2
1
0
a1=. ({.`)(`{:)(`:6)
a1=. (({.`'') , ] , ({:`'')c) hg
a1=. train o ({.cv ; ] ; {:cv) f.adv
Discussion
First solution,
a1=. ({.`)(`{:)(`:6)
This classic orthodox form illustrates a combination of the two basic
building forms. For a general explanation see the link in Dan's post [0]
(together with another solution based on @. by Pascal).
Second solution,
a1=. (({.`'') , ] , ({:`'')c) hg
This form illustrates the general "holy grail" method for producing adverbs
via the form v hg; hg is defied in the post [1]. The verb v transforms
the atomic representation of the argument of v hg into the gerund whose
train is the desired product of the adverb v hg. A sequence of steps for
building v (and consequently the adverb a1) are shown, in a session excerpt
(edited for clarity), below,
c =. "_
* ( ] ) hg
*
* (({.`'') , ] ) hg
{. *
* (({.`'') , ] , ({:`'')c) hg
{. * {:
u (({.`'') , ] , ({:`'')c) hg
{. u {:
a1=. (({.`'') , ] , ({:`'')c) hg
Third solution
a1=. train o ({.cv ; ] ; {:cv) f.adv
This form illustrates the general "sorcerer's cauldron" method for
producing adverbs via the form v adv; adv is defined in the post [2]. The
verb v transforms directly the argument of v adv into the desired
product of the adverb v adv. A sequence of steps for building v (and
consequently the adverb a1) are shown, in a session excerpt (edited for
clarity), below,
* ] f.adv
*
* ({.cv ; ] ) f.adv
┌──┬─┐
│{.│*│
└──┴─┘
* ({.cv ; ] ; {:cv) f.adv
┌──┬─┬──┐
│{.│*│{:│
└──┴─┴──┘
* train o ({.cv ; ] ; {:cv) f.adv
{. * {:
u train o ({.cv ; ] ; {:cv) f.adv
{. u {:
a1=. train o ({.cv ; ] ; {:cv) f.adv
The adverb cv produces a wicked verb that produces the argument of the
adverb cv regardless of the argument taken by the wicked verb; in that
sense cv is a generalization of "_, for example,
{.cv _
{.
({.cv _) 2 3 5 7
2
Writing cv is a challenging exercise and a solution can be found, of
course, in the J Wicked Toolkit found in the post [2].
The sentence train o ({.cv ; ] ; {:cv) produces the {. u {: train
(naturally) and its variations are so handy that can be simplified; for the
example at hand, as [: {.cv ] {: Train where Train is a recurrent
adverb emulating strand notation (aka, multiple adverb). Versions of this
adverbs, able to run on an official J interpreter (Jo), are coming in the
near future to the Jym.
References
[0] [Jprogramming] Adverbial Tacit Jym
http://www.jsoftware.com/pipermail/programming/2016-March/044743.html
[1] [Jprogramming] Adverbial Tacit Jym
http://www.jsoftware.com/pipermail/programming/2016-March/044789.html
[2] [Jprogramming] Tacit Toolkit (was dyadic J)
http://www.jsoftware.com/pipermail/programming/2015-December/043757.html
On Sun, Mar 13, 2016 at 10:59 PM, Jose Mario Quintana <
[email protected]> wrote:
> Welcome to the Adverbial (and Conjunctional) Tacit Jymnasium :)
>
> Orthodox and wicked routines will be practiced here for those interested
> in developing adverbial (and conjunctional) tacit muscles. Official
> interpreters will be the standard equipment; however, Unbox, Jx, and other
> J interpreters (including Golden Age J interpreters), as well as Toolkits ,
> see for example [0], and alike (e.g., the tacit translator), are in general
> more than acceptable although occasionally some restrictions might be
> imposed aiming to develop certain muscles. Since adverbial (and
> conjunctional) tacit writing can (following two closely related approaches)
> be reduced to verbal tacit writing, this is also a place to exercise verbal
> tacit muscles. In addition, some adverbs (and conjunctions) which will be
> eventually shown here can provide general support for producing tacit
> verbs, adverbs and conjunctions.
>
> Instructors will describe an exercise and, unless otherwise specified in
> advance, will be prepared to show at least one way to perform it if patrons
> (including other instructors) have not performed the exercise after a
> reasonable time; alright, they have bragging rights either way ;) The
> exercises would typically involve producing adverbs with bonus points for
> producing fixed versions of the adverbs and their products. Exercises are
> not required to be brand new. Given credit to the originators of certain
> techniques is not necessary (but you know who you are and bragging is
> allowed). Spoiler alerts by instructors and patrons will be appreciated.
>
> Instructors (Dan, Thomas et al. are you listening?), not to mention
> patrons (including beginners), are all very welcome here. How long will
> the Jym remain open? Indefinitely, as long as there enough patrons and
> instructors or we are kicked out of here.
>
> Let us start with a few exercises with different degrees of difficulty
> (feel free to ask any questions just be patient with me, sometimes I
> disappear for a few days):
>
>
> - Exercise 0. Rank infinity
>
> Produce a (tacit, of course) adverb a0 such that u a0 produces u"_
> where u is a noun or a verb, for example,
>
> u a0
> u"_
>
> *:@:(+/) a0
> *:@:(+/)"_
>
> u=. 1 2 3
>
> u a0
> 1 2 3"_
>
> 1 2 3 a0
> 1 2 3"_
>
>
> - Exercise 1. Operating on the first and last items
>
> Produce an adverb a1 such that u a1 produces {. u {: where u is a verb,
> for example,
>
> erase'u'
> 1
>
> u a1
> {. u {:
>
> * a1
> {. * {:
>
> * a1 2 3 5 7
> 14
>
>
> - Exercise 2. Back insert
>
> Produce an adverb a2 which is a tacit counterpart of the explicit adverb
> rscan, see [1],
>
> rscan=. 1 : '((>: - m |&# y) |. m)/y'
>
> for example,
>
> (+`%`* rscan\. ,: +`%`* a2\.) 1 2 3 4 5 6 7
> 1.16184971 0.161849711 12.3571429 4.11904762 0.119047619 42 7
> 1.16184971 0.161849711 12.3571429 4.11904762 0.119047619 42 7
>
> (+`-`*`% rscan\. ,: +`-`*`% a2\.) 1 2 3 4 5 6 7 8
> _0.6 1.6 0.8 3.75 _0.25 5.25 0.875 8
> _0.6 1.6 0.8 3.75 _0.25 5.25 0.875 8
>
>
> - Exercise 3. Replace items
>
> Produce an adverb a3 which is a tacit counterpart of the explicit adverb
> ritem, see [2],
>
> ritem =: 1 : (':' ; 'x (I.m-:"_1 _ y) } m')
>
> for example,
>
> C=. 3 4$i.8
> A=. i.3 2 4
>
> assert 9 8 7 6 (C ritem -: C a3) 0 1 2 3
> assert (100%i.2 4) (A ritem -: A a3) 16+i.2 4
>
>
> References
>
> [0] [Jprogramming] Tacit Toolkit (was dyadic J)
>
> http://www.jsoftware.com/pipermail/programming/2015-December/043757.html
>
> [1] [Jprogramming] Am I understanding m/y ?
>
> http://www.jsoftware.com/pipermail/programming/2016-February/044483.html
>
> [2] [Jprogramming] Replace Items
> http://www.jsoftware.com/pipermail/programming/2016-March/044625.html
>
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